1. Field of the Invention
The present invention relates to recording media, a recording and reproducing apparatus, and a method for recording and reproduction, and in particular, to recording media that, for example, makes it possible to protect contents stored in the recording media from copying, to enable or disable accesses to the contents, or to perform other managing operations, a method for authentication using the recording media, and an authenticating system that can execute the method for authentication.
2. Description of the Related Art
The prevalence of digital data has been increasing the importance of a copy protection technique used to protect the copy rights of video software, application software, and the like. Typical examples of software which require copy protection include DVDs (Digital Versatile Disk) or DVD-ROMs which employ a digital recording system. An enciphering technique is conventionally used for the copy protection of video software for digital recording.
The copy protection method using the enciphering technique has already been effectively functioning for DVDs or DVD-ROMs on which enciphered data is recorded. However, the problems described below may occur in DVD-RAMs on which users can newly record data.
(1) It is difficult to manage a “private key” required for enciphering.
(2) It is difficult to execute an effective enciphering process with data recording and reproducing apparatuses easily available to users, for example, DVD-RAM recorders or the like which enable digital recording and reproduction in the same manner that widespread analog video cassette recorders enable recording and reproduction. With these apparatuses, the cipher is likely to be attacked.(3) If the data recording and reproducing apparatus can execute an enciphering and deciphering processes, data contents to be protected from copying are easily copied by deciphering data created and enciphered by a user, using another data recording and reproducing apparatus, and then executing an enciphering process again.
These problems make it difficult to allow copy protection using a conventional enciphering technique to function effectively for recording and reproducing apparatuses for digital video data. Further, when a DVD-RAM drive uses its own method to execute a copy protection process on DVD-RAM data recording media, if a DVD-ROM drive reproduces data from the data recording media or conversely the DVD-RAM drive reproduces data from a DVD-ROM disk, a copy protection processing circuit must disadvantageously be complicated. This also increases product costs for the DVD-RAM drive.
The inventor has proposed, in Jpn. Pat. Appln. KOKAI Publication No. 2004-39006, recording media that enable copy protection for recorded data to be realized by providing the media with an authentication region in which RAM bits and ROM bits are arranged; the data in the RAM bits can be rewritten under a first write condition, and data cannot be written to the ROM bits under the first write condition.
On the other hand, in recent years, much attention has been paid to discrete track media in which adjacent magnetic recording tracks are separated from one another by grooves or guard bands consisting of a nonmagnetic material to reduce the magnetic interference among the adjacent tracks; the objective of using the discrete track media is to deal with the further increased density of magnetic recording media. To manufacture such discrete track media, an imprinting method is executed to form patterns of a magnetic substance and a nonmagnetic substance using a stamper; the magnetic substance constitutes magnetic recording tracks.
The recording media disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2004-39006 enables reliable copy protection to be realized. However, it has been desirable to achieve copy protection using a simpler method.